1. Field of the Invention
The present invention relates to a communication apparatus connectable to a network via a digital interface.
2. Related Background Art
There are many digital device having a digital interface for communications with external devices and the like. Such digital devices are interconnected through digital interfaces so that a network system can be configured. Conventionally, one network system has been configured by using only one type of digital interfaces, and it is difficult to configure the network system using different types of digital interfaces.
As one method of solving this problem, UPnP (Universal Plug and Player) has been proposed (Reference Document 1: Universal Plug and Play Device Architecture, Version 1.0, 08 Jun. 2000). UPnP performs communications among different interfaces by using the IP (Internet Protocol). UPnP can therefore configure a network system using different types of interfaces, independently from transmission media compatible with interfaces.
FIG. 9 shows an example of a network system in conformity with UPnP (hereinafter called a UPnP network system). Referring to FIG. 9, a DTV 103 as a control point can detect and control a DVCR 104 as a device. However, DTV 103 and DVCR 104 are not directly connected through a transmission medium capable of data communications in conformity with the IEEE1394 Standard (Reference Document 2: IEEE Std 1394-1995, IEEE Standard for a High Performance Serial Bus, Institute of Electrical and Electronics Engineers, Inc.), and DTV 103 cannot receive moving image data from DVCR 104 using the IEC61883 protocol (Reference Document 3: IEC 61883-1, Consumer audio/video equipment—Digital interface—Part 1: General). Therefore, in the UPnP network such as shown in FIG. 9, even if a user operates a panel for controlling DVCR 104 displayed on the display screen of DTV 103, a reproduced image will not be displayed on the screen. Even if each device connected to the UPnP network operates normally, a user may judge that the device is out of order.